Question

the oca2 gene encodes the p protein, a transmembrane protein that influences eye color in humans.
a researcher collected dna from individuals and used dna sequencing to identify the order of nucleotides in the oca2 gene for each individual. a subset of the sequencing data, which shows the results for two individuals, is shown in figure 1.
figure 1: dna sequencing data for positions 905 - 918 of the oca2 gene in two humans.
which of the following can be determined from the data in figure 1?
choose 1 answer:
(a) human 1 has better vision than human 2 does.
(b) human 1 makes more p protein than human 2 does.
(c) human 1 and human 2 are identical twins.
(d) human 1 and human 2 have different alleles of the oca2 gene.

Explanation:

• Option A: DNA sequencing data of the OCA2 gene (related to eye color) does not provide information about vision quality. So this is incorrect.
• Option B: The data shows DNA sequences, not protein production levels. There's no info on how much P protein each human makes. Incorrect.
• Option C: Identical twins have nearly identical DNA. The sequences here (e.g., at position 915, Human 1 has C and Human 2 has T) differ, so they aren't identical twins. Incorrect.
• Option D: Alleles are different forms of a gene. The DNA sequences of the OCA2 gene for Human 1 and Human 2 differ (e.g., position 915: C vs T, position 917 - related? Wait, looking at the sequences: Human 1 at positions 915 - 917: C C G G G? Wait, the sequence for Human 1: positions 905 - 918: C A T C A G C A T C C G G G. Human 2: C A T C A G C A T C T G G G. So at position 915 (let's count: 905 (C), 906 (A), 907 (T), 908 (C), 909 (A), 910 (G), 911 (C), 912 (A), 913 (T), 914 (C), 915 (C for Human 1, T for Human 2), 916 (G for Human 1, G for Human 2? Wait no, Human 1: after 914 (C) is 915 (C), 916 (C), 917 (G), 918 (G)? Wait the figure: Human 1's sequence at positions 905 - 917: C A T C A G C A T C C G G G (positions 905 - 917: 13 bases? Wait maybe counting: 905 (1), 906 (2), 907 (3), 908 (4), 909 (5), 910 (6), 911 (7), 912 (8), 913 (9), 914 (10), 915 (11), 916 (12), 917 (13). Human 1: positions 11 - 13: C, C, G? Wait no, the text: Human 1: C A T C A G C A T C C G G G. Human 2: C A T C A G C A T C T G G G. So at position 11 (915) and 12 (916)? Wait, the key is the DNA sequences differ, so they have different alleles of the OCA2 gene. Correct.

Answer:

D. Human 1 and Human 2 have different alleles of the OCA2 gene.